This invention pertains generally to die cutting. More specifically, this invention relates to anvil covers for use in conjunction with die cutting apparatus.
In the rotary die cutting art, rotary anvil constructions employ covers of tough resilient material, such as rubber, synthetic rubber, polyurethane, and the like, against which the cutting dies work. U.S. Pat. Nos. 3,522,754; 4,073,208; 3,282,142; 3,274,873; and 4,073,207 disclose a number of typical rotary anvil constructions. These patents also disclose several variations of removable anvil covers. The primary function of these covers is to provide a relatively tough uniform surface against which the sharp blade of a die cutter will work when cutting thin sheets or webs such as cardboard, corrugated paper or the like. To be of practical use, such removable covers should be relatively long lasting, inexpensive to manufacture, readily restorable or cheap enough to be disposable, and easy to mount and remove so as to avoid excessive downtimes during replacement.
Those concerned with the development of such removable anvil covers have long recognized that long cover life is best achieved when the cover provides a uniform resistance to the cutter penetration during operation. As can been seen from the above cited patents, attempts to develop such long lasting, easily replaceable anvil covers have included cover and anvil combinations with ribs, grooves, reinforcing materials, interlocking lugs, recesses, and a variety of other complex mounting structures. Although prior art cover structures have resulted in some success at providing more uniform cutting surfaces, thereby increasing cover life, many have been unduly complex. As such, many prior art covers have proved to be relatively expensive to manufacture and often cumbersome to use. For example, it is generally felt that many available covers are unduly time consuming for an operator to mount or replace when worn, thereby resulting in unnecessary downtime. Additionally, many prior art covers have been found to be so complex that users desiring to incorporate them into their present equipment normally have to bear the enormous expense of replacing the entire drum-anvil-cover combination.